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Even overpriced, it seems to be the best torso for spider popes. Or at least better than segmented ribcages, which take at least one more action to make into a spider (no tail slot on carapace).
Leaving off the value of the legs (cancelled out of the equation), the value of the skeletons plus theology is: Segmented - 67.50 (60 from theology, 7.50 torso/head/tail) Carapace - 70 (60 from torso + 100 from theology - 90 from being overpriced)
During spider weeks this is more pronounced as you are boosting 60 instead of 7.50.
And since it takes fewer actions to fill up a carapace, better EPA.